Commercially viable radiation-curable silicones for different coating applications have been the goal of recent research investigations. In the course of such investigations, there have been taught epoxysilicon/'onium catalyst systems, U.S. Pat. Nos. 4,279,717 and 4,421,904; various acrylated and methacrylated silicones, U.S. Pat. Nos. 4,348,454 and 4,558,082; perbenzoate photocatalyzed silicone terpolymers, U.S. Pat. No. 4,558,147; and mercaptan functional silicone polymers, U.S. Pat. No. 4,595,471, among others.
A radiation-curable silicone should be easy to produce, inexpensive to process, and "user friendly"; that is, present no special problems on application and cure if it is to be a commercially viable product. Seen in this light, epoxy silicones are high in cost, difficult to process, and have limited shelf stability in the presence of 'onium-type photocatalysts. Acrylated or methacrylated silicone compositions require efficient inerting of the UV-cure chamber for fast, fully developed cure. Mercaptan vinyl-type silicone UV systems have excellent shelf stability and do not require inerting but are slow to cure and difficult to produce.
It is an object of the present invention to provide a simple and convenient method to produce a UV active silicon compound having mercaptan groups, radiation sensitive unsaturated carbon bonds or both, the method being characterized by the reaction of mercaptan with carbon unsaturation.
It is another object of the present invention to produce a UV active silicon compound having mercaptan groups, radiation sensitive unsaturated carbon bonds, or both, linked to the silicon compound by a thioether group,
It is yet another object of the present invention to provide a UV curable composition containing a silicon compound having mercaptan groups, radiation sensitive unsaturated carbon bonds, or both linked to the silicon compound by a thioether group.